The invention relates to security gates and more particularly to crash proof security gates.
There has in recent years been an increasing number of cases wherein terrorists have attacked military, government and industrial organizations by crashing a vehicle at high speed through barriers and gates erected at security entrances.
Inventors have in the past sought solutions for providing crash-resistant security barriers and gates.
U.S. Pat. No. 4,354,771 discloses a curb barrier with retractable curb modules.
U.S. Pat. No. 4,152,871 discloses a vehicle barricade with a barrier plate that can be raised or lowered with hydraulic pressure.
U.S. Pat. No, 4,101,235 discloses an exit control device having a barrier of retractable sharp spikes in the roadway.
U.S. Pat. No. 3,805,448 discloses a vehicle traffic control apparatus having pivotal plates that can be hydraulically raised from the road surface.
U.S. Pat. No. 3,775,912 discloses an automatically operated vehicle gate with a locking mechanism.
U.S. Pat. No. 3,626,638 discloses a wrong-way traffic safety barrier consisting of retractable barrier elements in the road surface.
U.S. Pat. No. 3,089,267 discloses a pushover gate that can be opened by pressure from a motor vehicle but is resistant to livestock.
With increasing militancy shown in recent years by terrorists in many parts of the world it appears that none of the prior art teaches a vehicle barrier of high crashworthiness when attacked by a heavy vehicle moving at high speed against the barrier.